gtk-gnutella problems

Sid upgraded my gtk-gnutella to gtk-gnutella 0.96.1svn12109-1. And
now it does not work. I appear to be firewalled. AFAIK, I have the
right ports in my firewall forwarded (shorewall); this has worked
for years. gtk-gnutella told me that the version is "too old"
(although it is the newest one), and I had to add a line to
~/gtk-gnutella/config.gnet, which I did. However, no contact with
the gnutella network is established when the program starts.
Maybe something is wrong with the new Sid version (although
downgrading to the stable version also does not help). Maybe
something changed in the gnutella network itself. I use
gtk-gnutella fairly rarely, so this problem may actually not be
very recent.
Grateful for any hints,
Regards, Jan